*4.4. Anthocyanin Pigment Extraction from Red Onion Peel*

For the extraction of anthocyanin from red onion peel, 10 g sections of fresh red onion (*Allium cepa*) peel were washed with tap water to remove impurities. Clean wet peels were then dried in an oven at 50 ◦C for 24 h. Dried peels were then grounded to obtain a powder. To extract anthocyanin, 10 g of clean, dried onion peel powder was dispersed in 40 mL of acidified ethanol and 1% ascorbic acid, and the mixture was stirred for 1 min using a magnetic hot plate stirrer (GFL, Korea). The solution was incubated overnight at 30 ◦C in an oven (Binder) for the extraction and recovery of anthocyanin pigments. The obtained solution was filtered using Whatman filter paper (540), after which the solvent was evaporated using a rotary evaporator (Franklin Electric, UK) at 40 ◦C to obtain dry powdered anthocyanin. The obtained anthocyanin pigment powder was stored in a sterile container for further use.
